Pavement marking tapes are typically used to delineate the boundaries for lanes of traffic on a roadway. The tape may extend continuously, such as along the outermost boundaries of the driving lanes, or intermittently, such as between lanes. One popular use for such a tape is in construction work zones, where pavement marking tape can guide motorists through new traffic patterns without incident. Typically, the pavement marking tapes are eventually removed from the roadway. To allow the pavement marking tape to be peeled from the surface of the roadway in a single piece, the marking tape must have sufficient structural integrity to prevent tearing. Further, if the tape is intended to remain in place indefinitely, it is necessary to provide structural integrity sufficient to withstand the abuse that vehicles and weather can impose.
U.S. Pat. No. 4,117,192 (Jorgensen) relates to a pavement marking sheet materials made from deformable, reduced-elasticity polymeric materials that are made retroreflective by adhering to the sheet material a thin support film having retroreflective elements partially embedded in it. The exemplified sheet material contains 23 parts by weight acrylonitrile-butadiene elastomer precursor, 19.6 parts chlorinated paraffin, 27.6 parts “Asbestos RG 144”, 29.9 parts titanium dioxide, 4.6 parts synthetic silica, and 0.8 parts stearic acid.
U.S. Pat. No. 4,282,281 relates to a longer-lived pavement marking that is provided by adhering to the pavement a sheet material about one fourth millimeter or more thick that comprises a carboxyl-modified acrylonitrile-butadiene polymer and particulate fillers dispersed in the polymer. The exemplified sheet material contains 13.53 parts by weight carboxyl-modified acrylonitrile-butadiene elastomer precursor having 5 weight-percent carboxyl functionality, 11.5 parts by weight chlorinated paraffin, 17.59 parts by weight titanium dioxide, 0.07 parts by weight Ultramarine blue pigment, 16.24 parts by weight asbestos (“Calidria RG-100”), 0.48 parts by weight stearic acid, 2.71 parts by weight hydrated silica, and 37.89 parts by weight glass microspheres averaging 200 micrometers in diameter treated with 550 parts per millions of an aminosilane. Others sorts of particulate or fibrous fillers may also be used, such as clay, talc, wood flock or glass fiber.
According to U.S. Pat. No. 5,373,465 (Fulcomer) “Asbestos fibers contribute importantly to the desired properties of the sheet material, but for toxicity reasons, use of such fibers has been virtually eliminated for many applications. Alternative fillers, such as polyethylene fibers as disclosed in U.S. Pat. No. 4,490,432 to Jordan, or reinforcing cellulose fibers, as disclosed in U.S. Pat. No. 5,139,590 to Wyckoff may substitute for asbestos filling material.”
U.S. Pat. No. 4,490,432 (Jordan) relates to a pavement-marking sheet material which comprises a non-crosslinked elastomeric precursor such as acrylonitrile-butadiene polymer; a thermoplastic polymer such as polyethylene which reinforces the sheet material, e.g., by orientation of the thermoplastic polymer so that the calendered product exhibits greater tensile strength downweb than crossweb; and a particulate inorganic filler, which preferably includes platelet-type fillers such as talc, mica, or magnesium silicate.